Sudden Ringneck Pheasant chick death- need help finding cause

Hello BYC, I am in need of help with finding out the cause of death of one of my four ringneck pheasant chicks, which passed on this morning. I last saw it alive around 6:00-6:30 am this morning, looking and acting just fine. I then slept for about another three hours and woke up to see a chick on its side, dead and already stiff. The chicks are probably a few days old, the dead one has its eyes partially open and its legs are extended away from its body; if it were picked up by the neck the legs would be pointing towards the ground.

I would really appreciate it if someone had any information on possible cause of death. I keep them in a pen under a heat lamp and the chicks are not gathering under the lamp all the time or trying to get away from it all the time, so I don't think the death was due to temperature extremes. I have checked the first couple pages of pheasant-related threads and found nothing. I would like to determine cause of death ASAP becausef if it was a disease, the other chicks may be in danger and I may have to take them to a vet. Also please let me know if I need to give more info or clarify anything, if that would help anyone figure out what happened to it. Thanks everyone

Sorry for your loss. Was the chick under the heat lamp when you found it? The reason i ask, is because i've had chicks that would lay directly under the lamp and not move, then it was too late and got heat stroke. I 've saved 2 this season already from them laying there until heat stroke set in. It's kinda rare but does happen.